Fuel injectors are well-known devices for injecting fuel into engines, either into an intake manifold upstream of a combustion chamber, or directly into the combustion chamber. It is highly desirable that the fuel spray be well atomized for rapid vaporization, and mix appropriately with air, in order to achieve optimal combustion and power generation while minimizing formation of undesirable byproducts of combustion, and preventing uncontrolled combustion events.
Engineers are developing spark ignition engines with direct fuel injection (SIDI) which operate using a stratified combustion charge strategy and a homogeneous combustion charge strategy, depending upon operator demand for power and engine operating conditions. The SIDI engines are being developed to improve engine fuel efficiency and thus improve vehicle fuel economy. Generally, an SIDI engine is preferably operated at high load conditions with a homogenous charge. And, an SIDI engine is preferably operated at low load conditions with a stratified charge. Homogeneous charge is most readily achieved with a wide fuel injection spray cone angle whereas stratified charge is most readily achieved with a narrow fuel injection spray cone angle. Engineers make tradeoffs in designing fuel injectors to address the divergent low load and high load fueling requirements when selecting spray cone angles.